Recover subject name when called with pcall to get proper error messages

lua/gluatest/expectations/negative.lua

@@ -4,6 +4,7 @@ local IsValid = IsValid
 local isstring = isstring
 local string_format = string.format
 local GetDiff = include( "utils/table_diff.lua" )
+local DoPCallWithSubject = include( "utils/caller_recovery.lua" )
 
 -- Inverse checks
 return function( subject, ... )
@@ -178,7 +179,7 @@ return function( subject, ... )
     function expectations.succeed()
         assert( TypeID( subject ) == TYPE_FUNCTION, ".succeed expects a function" )
 
-        local success = pcall( subject, unpack( args ) )
+        local success = DoPCallWithSubject( subject, unpack( args ) )
 
         if success ~= false then
             i.expected( "to not succeed" )
@@ -189,7 +190,7 @@ return function( subject, ... )
     function expectations.err()
         assert( TypeID( subject ) == TYPE_FUNCTION, ".err expects a function" )
 
-        local success = pcall( subject, unpack( args ) )
+        local success = DoPCallWithSubject( subject, unpack( args ) )
 
         if success ~= true then
             i.expected( "to not error" )
@@ -202,7 +203,7 @@ return function( subject, ... )
         assert( TypeID( subject ) == TYPE_FUNCTION, ".errWith expects a function" )
         assert( isstring( comparison ), "errWith expects a string" )
 
-        local success, err = pcall( subject, unpack( args ) )
+        local success, err = DoPCallWithSubject( subject, unpack( args ) )
 
         if success == true then
             i.expected( "to error" )

lua/gluatest/expectations/positive.lua

@@ -4,6 +4,7 @@ local IsValid = IsValid
 local isstring = isstring
 local string_format = string.format
 local GetDiff = include( "utils/table_diff.lua" )
+local DoPCallWithSubject = include( "utils/caller_recovery.lua" )
 
 -- Positive checks
 return function( subject, ... )
@@ -177,7 +178,7 @@ return function( subject, ... )
     function expectations.succeed()
         assert( TypeID( subject ) == TYPE_FUNCTION, ".succeed expects a function" )
 
-        local success, err = pcall( subject, unpack( args ) )
+        local success, err = DoPCallWithSubject( subject, unpack( args ) )
 
         if success == false then
             i.expected( "to succeed, got: %s", err )
@@ -188,7 +189,7 @@ return function( subject, ... )
     function expectations.err()
         assert( TypeID( subject ) == TYPE_FUNCTION, ".err expects a function" )
 
-        local success = pcall( subject, unpack( args ) )
+        local success = DoPCallWithSubject( subject, unpack( args ) )
 
         if success == true then
             i.expected( "to error" )
@@ -201,7 +202,7 @@ return function( subject, ... )
         assert( TypeID( subject ) == TYPE_FUNCTION, ".errWith expects a function" )
         assert( TypeID( comparison ) == TYPE_STRING, ".errWith expects a string" )
 
-        local success, err = pcall( subject, unpack( args ) )
+        local success, err = DoPCallWithSubject( subject, unpack( args ) )
 
         if success == true then
             i.expected( "to error with '%s'", comparison )

lua/gluatest/expectations/utils/caller_recovery.lua

@@ -0,0 +1,134 @@
+-- As the name implies, finds the last occurrence of the given needle
+local function findLast( haystack, needle )
+    local lastPos = string.find( haystack, needle, nil, true )
+    local nextPos = lastPos and string.find( haystack, needle, lastPos + 1, true )
+    while nextPos ~= nil do
+        lastPos = nextPos
+        nextPos = string.find( haystack, needle, lastPos + 1, true )
+    end
+
+    return lastPos
+end
+
+-- Removes ( and ) without breaking stuff hopefully
+-- This means you can do crazy stuff like expect( test123(test456(test789(123))) ) which will be stripped to just test123
+local function removeBraces( line )
+    local findStartPos = findLast( line, "(" )
+    while findStartPos do
+        local findEndPos = string.find( line, ")", findStartPos + 1 )
+        if not findEndPos then break end
+
+        line = string.Trim( line:sub( 0, findStartPos - 1 ) .. line:sub( findEndPos + 1 ) )
+
+        findStartPos = findLast( line, "(" )
+    end
+
+    return line
+end
+
+
+--[[
+    Name recovery function for expect( test.123 )
+    to retrieve 123 so that functions like errWith will work properly if given directly the function that will error
+
+    This is mainly required due to Lua losing track of the caller function resulting in '?' inside an error message
+    you could always wrap it like this to workaround this issue: local testFunc = function(...) test.123(...) end
+    Using which this entire stuff would not be necessary, as then the function you pass to pcall will not be the one erroring.
+    and since you call your function inside of it, Lua still knows the name of it, causing errWith to work properly.
+]]
+local function GetExpectationSubjectName( additionalShift )
+    additionalShift = additionalShift or 0
+    -- We gotta figure out the caller name as its lost when we get called as it isn't kept track off
+    local ourDebugInfo = debug.getinfo( 2 + additionalShift, "n" ) -- Makes copy-pasting this easier (also allows us to move this somewhere else later)
+    local callerDebugInfo = debug.getinfo( 3 + additionalShift, "Sln" ) -- 3 = caller, 2 = expect.errWith or such, 1 = us
+    if callerDebugInfo and ourDebugInfo and ourDebugInfo.name ~= "" and callerDebugInfo.currentline ~= 1 then
+        -- ToDo: Cache the file content to reduce filesystem usage (Could quickly escalate, slowing everything down immensely)
+        local fileHandle = file.Open( callerDebugInfo.short_src, "rb", "GAME" ) --[[@as File]]
+        if fileHandle then
+            -- Skipping to our current line
+            for _ = 1, callerDebugInfo.currentline - 1 do
+                fileHandle:ReadLine()
+            end
+            local line = string.Trim( fileHandle:ReadLine() )
+            fileHandle:Close() -- No longer need our handle
+
+            -- Remove expected
+            local _, findPos = string.find( line, "expect" )
+            if findPos then
+                line = string.Trim( line:sub( findPos + 1 ) )
+            end
+
+            -- Remove everything after "errWith" including itself
+            findPos = string.find( line, ourDebugInfo.name )
+            if findPos then
+                line = string.Trim( line:sub( 0, findPos - 1 ) )
+            end
+
+            -- First remove the left over . from ".errWith" as we only removed errWith
+            findPos = findLast( line, "." )
+            if findPos then
+                line = string.Trim( line:sub( 0, findPos - 1 ) )
+            end
+
+            -- Now remove the ".to"
+            findPos = findLast( line, "." )
+            if findPos then
+                line = string.Trim( line:sub( 0, findPos - 1 ) )
+            end
+
+            -- Remove leftover "(" wrapping
+            if line:StartsWith( "(" ) then
+                line = string.Trim( line:sub( 2 ) )
+            end
+
+            -- Remove leftover ")" wrapping
+            if line:EndsWith( ")" ) then
+                line = string.Trim( line:sub( 0, line:len() - 1 ) )
+            end
+
+            line = removeBraces( line )
+
+            -- Now, finally remove the the rest in case it had arguments like expect( test123, 123 )
+            findPos = string.find( line, "," )
+            if findPos then
+                line = string.Trim( line:sub( 0, findPos - 1 ) )
+            end
+
+            findPos = findLast( line, "." )
+            if findPos then
+                line = string.Trim( line:sub( findPos + 1 ) )
+            end
+
+            findPos = findLast( line, ":" )
+            if findPos then
+                line = string.Trim( line:sub( findPos + 1 ) )
+            end
+
+            return line
+        end
+    end
+
+    return "?"
+end
+
+local function DoPCallWithSubject( subject, ... )
+    local callerName = GetExpectationSubjectName( 1 ) -- 1 since this function also shifts things again
+
+    __GLUA_RUN = {} -- To not conflict and to avoid setting up an entire fenv
+    local callSubject = callerName ~= "?" and CompileString( [[__GLUA_RUN.]] .. callerName .. [[( ... )]], "", false ) or subject
+    -- Instead of doing __GLUA_RUN_callerName, we do __GLUA_RUN.callerName
+    -- so that the name won't be modified in the resulting error messsage as it ignores the table name
+    __GLUA_RUN[callerName] = subject
+
+    local success, err = pcall( callSubject, ... )
+    __GLUA_RUN = nil -- Cleanup :^
+
+    -- This can exist because of the use of CompileString, so nuke it
+    if err and err:StartsWith( ":1: " ) then
+        err = err:sub( 5 )
+    end
+
+    return success, err
+end
+
+return DoPCallWithSubject

lua/tests/gluatest/expectations/callerRecovery.lua

@@ -0,0 +1,17 @@
+---@diagnostic disable: param-type-mismatch
+return {
+    groupName = "callerRecovery",
+    cases = {
+        {
+            name = "Called function name is included in error message",
+            func = function()
+                -- This never worked, instead of 'Left' it had given '?'
+                expect( string.Left, nil ).to.errWith( "bad argument #1 to 'Left' (string expected, got nil)" )
+
+                -- This is how it always had worked fine
+                local testFunc = function() string.Left( nil, nil ) end
+                expect( testFunc ).to.errWith( "bad argument #1 to 'Left' (string expected, got nil)" )
+            end
+        }
+    }
+}